With increase in the number of semiconductor devices packed on a single printed circuit board, more importance is being placed on the issue of heat dissipation from printed circuit boards having thereon heat-generating electronic components. For a heat-dissipating mechanism, creation of a heat conductive path for connecting a high temperature region to a low temperature region has been proposed. As products capable of having such a heat conductive path created therein, various heat-dissipating sheets have been developed. A heat-dissipating sheet is required to have steady levels of heat conductivity, strength, and shielding ability. Therefore, to improve heat conductivity and other properties of a heat-dissipating sheet, a composition comprising a graphite material is being considered for use in sheet form.
For example, Patent Literature 1 proposes a heat conductive composition comprising: graphite particles having an aspect ratio in a range of 10 to 20, and an average particle size of 10 to 200 μm; and a matrix of thermosetting resin with the particles dispersed therein.
Patent Literature 2 proposes an elastomer composition comprising: pitch carbon fibers or graphite chips; and an elastomer component with the fibers or chips dispersed therein. Here, the pitch carbon fibers are short fibers of 150 μm to 2 mm; and the graphite chips are 10 μm to 150 μm in thickness, 100 μm to 1 mm in width, and 150 μm to 2 mm in length.